The proposed research investigates human classical conditioning through the experimental study of a clinical phenomenon observed in cancer patients (anticipatory nausea during repeated cycles of chemotherapy). According to the classical conditioning explanation of this phenomenon, anticipatory nausea occurs because clinic stimuli repeatedly associated with the administration of emetogenic chemotherapy become conditioned stimuli whose presence alone can elicit nausea. The proposed program of research will be the first to experimentally test the conditioning theory of anticipatory nausea. To do this, we will systematically manipulate the stimuli associated with chemotherapy using procedures derived from experimental conditioning studies, and then determine whether anticipatory nausea is reduced. One of the manipulations will be to expose patients to an experimental stimulus in association with each chemotherapy administration. The repeated pairing of this stimulus with chemotherapy is expected to contribute to reductions in anticipatory nausea. In addition, the experimental stimulus is expected to become a conditioned stimulus for nausea. The demonstration of a conditioned nausea response to a stimulus under complete experimental control will provide the first conditioning model of anticipatory nausea. This model will then be used to experimentally test whether conditioning processes can be used to reduce the explicitly conditioned nausea response. The specific aims are: 1) To test the conditioning theory of anticipatory nausea by experimentally manipulating the stimuli associated with chemotherapy and examining the effect on anticipatory nausea; 2) To explore the possibility that experimental manipulations of stimuli associated with chemotherapy will provide ways to prevent the clinical problem of anticipatory nausea; 3) To develop a conditioning model of anticipatory nausea by explicitly pairing experimental stimuli with chemotherapy administration and then examining the response to those stimuli under controlled conditions; and 4) To use the experimental model to test whether the conditioning processes of latent inhibition and blocking can be used to reduce the explicitly conditioned nausea response.